2 Given the equation for cos(a+b) determine what the cos(2a)=? Hint think of a way to represent 2a by adding.​

Which two properties of equality could zoe use to finish solving for x? the equation is 3x - 4 = -10 for x so a either the addition or subtraction property of equalityb ether the multiplication or division property of equality c ether the addition or division property of equality d ether the subtraction or division property of equality just a simple a b c or d plz.